A person who advocates for or practices dissolution; someone who supports the break-up or dismantling of existing structures or unions.
From dissolution + -ist (suffix forming nouns for people who practice or believe in something). This creates an agent noun from the abstract concept.
Before the Civil War, American abolitionists were sometimes called 'dissolitionists' because opponents claimed they wanted to dissolve the Union—it was a harsh political slur that revealed how deeply connected slavery was to national identity.
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